“Comets are like cats. They have tails and they do precisely what they want.’’ — Astronomer David Levy
Another celestial tabby is about to promenade past us. With luck, it will purr and rub against our ankles, rather than turn tail with barely a nod our way.
Comet 46P/Wirtanen is about to get very close to Earth in December — only 7.2 million miles away. It will be the 10th closest comet pass in modern times.
If it brightens enough — as many astronomers expect it to do — people may be able to see it with their naked eyes, making it the brightest comet of the past few years.
“Let’s put it this way,” said Richard Talcott, senior editor of Astronomy Magazine. “As comets go, this should be a pretty good one.”
Which has put area astronomers on alert.
“We haven’t seen it yet,” said Monty Robson of the John. J. McCarthy Observatory at New Milford High School. “But we’ll be looking for it. It’s within our range.”
And because Comet Wirtanen will be most visible, high in the sky, near the Pleiades in the middle of December, it will coincide with the Geminid meteor shower — traditionally one of the best of the year.
Which means, if the night skies are clear, there will reasons for serious skywatching parties.
Robson said the McCarthy Observatory will almost certainly have a public event in mid-December.
New Pond Farm in Redding, in conjunction with The Discovery Center in Ridgefield, already has a date set — Dec. 15 at 6:30 p.m. To register, go to the Discovery Center’s website at ridgefielddiscovery.org or New Pond’s at newpondfarm.org
“All in all, it should be a pretty good night,” said Cliff Wattley of Ridgefield, who leads the skywatch events at New Pond Farm.
Comets are either dirty snowballs or snowy dirtballs that orbit around our solar system. When those orbits take them close to the sun, some of their mass melts, with the debris flowing behind creating their tails. When that debris hits the Earth’s atmosphere, we see it as a shooting star.
There are billions, even trillions, of comets in the Oort Cloud and Kuiper Belt at the outer edge of the Solar System. Humans — who have been watching them for millennia, first in fear, then scientifically — have identified 5,253 of them.
Astronomer Carl Wirtanen first identified the comet named after him in 1948 at the Lick Observatory in San Jose, Calif.
Unlike some faraway visitors, Comet 46P/Wirtanen is part of the neighborhood. Its orbit takes it around Jupiter and back, circling the sun every 5.4 years. It’s also relatively small, with a diameter of three-quarters of a mile.
What makes it special this year is simply that its orbit is bringing it closer to Earth than it usually does. As it gets closer to the sun, it should brighten enough to see easily with binoculars or a telescope.
Brighten some more, and it becomes a naked-eye object — a fuzzy cotton ball of light amid the star’s sharper points.
Talcott, of Astronomy Magazine, said what also makes Comet Wirtanen good for ordinary skywatchers is that it will be accessible. People can view it around 9:30 to 10 p.m. rather than at 3 a.m. Rather than hanging low near the horizon, it will be high in the sky.
What astronomers don’t know is whether Wirtanen will show off or be a no-show.
“It’s anybody’s guess,” said Geoff Chester, spokesman for the U.S. Naval Observatory in Washington.
Chester said 1973’s Comet Kahoutek was the most celebrated celestial dud of recent years.
“It was billed as the comet of the century,” Chester said. “It was more like the comet of the month.”
On the other hand, in 2007 Comet Holmes flared much brighter than any estimation. And two recent comets — Hyakutake in 1996 and Hale-Bopp in 1997 — lived up to their advanced notices and were breathtaking.
The Geminids — which peaks Dec. 12-14 — is the product of debris the object known as 3200 Phaethon leaves as it orbits through the solar system.
Phaethon was once classified as a asteroid. Today astronomers think it might be something completely different — a dormant comet, a rock comet.
“The Geminids are special,” Robson of the McCarthy Observatory in New Milford said.
Combine them with a living comet and mid-December could a great night for looking at the heavens.
“It could be spectacular,” Robson said.